NEGATIVE ACTIVE MATERIAL, PREPARATION METHOD THEREOF, SECONDARY BATTERY AND RELATED BATTERY MODULE, BATTERY PACK AND DEVICE

The present application discloses a negative active material, preparation process thereof and a secondary battery and the related battery module, battery pack and device. The negative active material comprises a core structure and a modified polymer coating layer coated on at least a part of the outer surface of the core structure, wherein the core structure comprises one or more of silicon-based materials and tin based materials; and wherein the negative active material has an infrared spectrum comprising an infrared absorption peak at the wavelength of 1450cm-1 to 1690cm-1, and the infrared absorption peak has a transmittance T that satisfies 80% ≤T≤99%.